Police say Carissa Williams was upset because the other driver was traveling the speed limit.
Investigators say Williams sped up and passed the victim, but they both ended up getting off at the same exit.
That's when Williams allegedly jumped out her car, jumped into the victim's vehicle and began shocking her.
According to investigators, 911 operators heard the victim yelling and screaming at Williams to stop because she was pregnant.
Police said the woman is 10 weeks pregnant, but she and the fetus are fine.
Williams was traveling with her own 10 month old in the car.
Police said Williams has a lengthy criminal history in four states.
She is being held on $100,000 bail.